1. Field of the Invention
The invention relates to the field of production of integrated circuits or microsystems and, more particularly, equipment for chemical vapour deposition.
2. Description of the Relevant Art
Integrated circuits or microsystems are produced from wafers or substrates which are generally composed of silicon or another semiconductor material and which are subjected to a succession of steps for depositing thin layers of various materials, masking and lithography of those layers then engraving of those layers. Between those steps for producing active elements of the devices there are interposed steps for cleaning the surfaces and inspection steps, in which the quality of the production methods is examined.
The present invention particularly relates to equipment for depositing layers which constitute integrated circuits and microsystems and, more particularly, equipment for chemical vapour deposition.
Various types of deposition are used in the technologies for producing integrated circuits and microsystems: so-called physical depositions (atomisation, evaporation) and so-called chemical depositions: chemical vapour deposition, atomic layer deposition, electrochemical deposition, to set out merely the main categories which are themselves subdivided into a plurality of sub-categories.
Physical depositions which more particularly involve the deposit of metal layers are carried out in pressure ranges of from a few nanobar to a few microbar. They have the advantage of being relatively simple to carry out because they use only neutral gases in order to carry out the depositions. Owing to their directional nature, however, they have the disadvantage of not uniformly covering patterns which have horizontal surfaces and vertical or quasi-vertical surfaces, such as the ones which appear in the production of integrated circuits and microsystems.
The rate of coverage of a surface by a physical deposit is directly proportional to the solid angle when viewed from that surface. As a result, the projecting portions and the horizontal surfaces of a pattern are covered with a thickness greater than the reflex angles or the vertical surfaces. Therefore, there results inhomogeneity of the deposits which may impair the correct operation of the electronic device produced.
In chemical depositions, there is brought about adsorption, chemical sorption or a heterogeneous reaction at the surface of the substrate to be covered. That adsorption, chemical sorption or reaction occurs at all the surfaces if adequate conditions involving temperature, pressure and the concentration of the reagents are combined in the case of a vapour phase deposition. As a result, the chemical depositions and particularly the chemical vapour depositions intrinsically cover in a uniform manner the surface of the patterns constituting the integrated circuits or microsystems. That characteristic is particularly advantageous in recent circuits or microsystems where the patterns to be covered may have very high form factors (relationship between the width and the height of the pattern).
The systems for producing integrated circuits or microsystems generally comprise a treatment chamber comprising a support for the substrate in the chamber.
A gas distribution assembly, also referred to using the term “showerhead”, provides one or more treatment gases near the substrate. The gases may be used to form a plasma. Such methods may comprise chemical vapour deposition (CVD), plasma enhanced chemical vapour deposition (PECVD) to deposit a layer on the substrate or an engraving reaction to remove material from the wafer.
In this regard, there are known documents U.S. Pat. No. 5,292,554, and U.S. Pat. No. 5,516,367, which have been adapted to old production technologies, International Patent Application Publication No. WO03/060185 and U.S. Patent Publication No. 2006/21703.
The Applicant became aware that known treatment chambers were liable to allow the occurrence of interference reactions between several gases upstream of the gas distribution assembly. Such interference reactions may deposit solids of powder-like form at undesirable locations. Furthermore, since the pressure upstream of the gas distribution assembly is higher than at the surface of the substrate to be covered, such interference reactions in the gas state are promoted.
Furthermore, the Applicant identified that the most recent materials whose use is envisaged in the field of integrated circuits and microsystems may involve the risk of the holes of the gas distribution assembly becoming clogged.
The invention is intended to improve the situation.